Reuse of Waste Plastics in Developing Countries: Properties of Waste Plastic-Sand Composites

Abstract

Waste plastics are a major problem in developing countries, where efficient collection and recycling systems often do not exist. Plastic bonded sand composites provide a low-cost recycling alternative for selected waste plastics. This research has investigated the production and properties of plastic bonded sand manufactured using low-density and high-density polyethylene (LDPE and HDPE). Plastic bonded sand production in The Gambia was used as a case study to identify potential barriers to the technology. Processing was done by oven moulding, or a heat-mixing technique, and the properties of the LDPE and HDPE bonded sand samples formed have been determined. Processing at temperatures between 250 °C and 325 °C produced optimum compressive and flexural strengths. Higher processing temperatures reduced strength and lower temperatures produced inhomogeneous samples. Thermal plastic degradation occurs at 400 °C in N2 and 250 °C in air. Processing at temperatures below 250 °C in anoxic conditions is necessary to control off-gases. The optimum sand addition to produce the highest compressive strength was between 65 and 80%, depending on the sand particle size. HDPE produced higher maximum compressive strengths (37.1 MPa) compared to LDPE (27.2 MPa). Plastic bonded sand has increased strength, toughness, ductility, and thermal conductivity compared to C20/25 concrete and sandcrete and it can be used for wall construction blocks and paving tiles. The potential applications and implications of processing waste plastics in developing countries into plastic bonded sand are discussed. Graphical Abstract

Recycling and reusing potential of disposable low-density polyethylene plastic waste for flexible paver tile construction for outdoor application

“…In addition to the primary materials, plastics often incorporate additives such as plasticizers, stabilizers, colorants, and fillers to enhance their properties for specific applications [ 10 , 33 ]. One of the key characteristics of plastics is their non-biodegradability, meaning they do not readily decompose in the environment [ 11 , 12 ]. This property has raised significant concerns regarding the environmental impact of plastic waste.…”

“…Repurposing plastic waste into paver tiles is an effective way to divert a significant amount of plastic from the waste stream. This practice contributes to more sustainable waste management practices [ 12 ]. This not only helps reduce the environmental impact of plastic waste but also promotes the concept of circular economy by beneficially reusing materials [ 12 , 25 ].…”

“…This practice contributes to more sustainable waste management practices [ 12 ]. This not only helps reduce the environmental impact of plastic waste but also promotes the concept of circular economy by beneficially reusing materials [ 12 , 25 ]. Additionally, paver tiles offer an ideal showcase for plastic waste recycling due to their durability and longevity [ 34 ].…”

“…Incorporating recycled plastic into paver tile production yields durable products capable of withstanding heavy foot traffic, vehicular loads, and diverse weather conditions. This approach enhances sustainability and circularity within the construction industry, offering environmentally friendly alternatives without compromising desired qualities [ 11 , 12 ]. Using recycled paving blocks promotes an eco-friendlier approach in the construction industry by reducing waste and promoting the concept of circular economy.…”

Modelling Water Absorption Index and Compressive Strength of Paving Stone Composites with Polyethylene Terephthalate (PET) as Total Binder Replacement

“…Several researchers have attempted to manage PET wastes by utilizing it as building materials [2][3][4][5][6][7][8]. Paving stone was categorized by [9].…”